Life Science Study Guide PDF

**Study Guide for Life Science** - **Stem Cell**: - A unique cell with the ability to develop into different cell types, including specialized cells for tissues and organs. - Plays a crucial role in growth, repair, and maintenance of the body. - **Tissue**: -...

**Study Guide for Life Science** - **Stem Cell**: - A unique cell with the ability to develop into different cell types, including specialized cells for tissues and organs. - Plays a crucial role in growth, repair, and maintenance of the body. - **Tissue**: - A group of similar cells working together to perform a specific function. - Examples include muscle tissue (movement), nervous tissue (communication), and epithelial tissue (protection). - **Organ**: - A structure made up of different types of tissues working together to carry out a specific function. - Examples include the heart (pumping blood), lungs (gas exchange), and kidneys (filtering waste). - **Sexual Reproduction**: - Involves two parents combining their genetic material to create offspring. - Requires specialized reproductive cells called **gametes** (eggs and sperm). - Leads to genetic variation in offspring. - **Asexual Reproduction**: - Involves only one parent and produces offspring genetically identical to the parent. - Common methods include: - **Fission**: Splitting of a single organism into two equal parts, e.g., bacteria. - **Budding**: Growth of a new organism as an outgrowth of the parent, e.g., yeast. - **Regeneration**: Ability of an organism to regrow parts, e.g., starfish. - **Vegetative Reproduction**: New plants growing from parts of the parent plant. - **Cloning**: Producing identical organisms artificially in a lab. - **Meiosis**: - A specialized type of cell division essential for sexual reproduction. - Reduces the chromosome number by half to produce **haploid cells** (eggs and sperm). - Two main stages: - **Meiosis I**: Homologous chromosomes separate, leading to genetic diversity. - **Meiosis II**: Sister chromatids separate, resulting in four unique haploid cells. - Importance: - Creates genetic variation through **crossing over** and **independent assortment**. - Ensures the stability of chromosome numbers across generations. - **Heredity**: - The biological process through which traits are passed from parents to their offspring. - Based on the transmission of **genes**, which carry instructions for specific traits. - Key features: - Each organism inherits two copies of every gene (one from each parent). - Traits can be **dominant** (visible in offspring) or **recessive** (hidden unless both alleles are recessive). - **Mendel\'s Contribution**: - Gregor Mendel, known as the \"Father of Genetics,\" conducted experiments with pea plants. - Discovered the basic principles of inheritance, such as dominance and segregation.\ \ Gregor Mendel, often called the \"Father of Genetics,\" was a scientist and monk who studied how traits are passed from one generation to the next. Mendel worked with pea plants and noticed that certain traits, like flower color and seed shape, were inherited in specific patterns. - **Traits come in pairs:** Each plant inherits one factor (gene) from each parent. - **Some traits are dominant:** These traits show up in the offspring even if only one parent passes them on. For example, tall plants were dominant over short plants. - **Some traits are recessive:** These traits only show up if both parents pass them on. For example, short plants appeared only if both factors were for shortness. - **Dominant Trait**: - A trait that is expressed when at least one dominant allele is present (e.g., brown eyes). - Masks the effect of a recessive allele in a heterozygous condition. - Represented by a capital letter (e.g., B for brown eyes). - **Recessive Trait**: - A trait that is only expressed when both alleles are recessive (e.g., blue eyes). - Represented by a lowercase letter (e.g., b for blue eyes). - **Gene**: A section of DNA that determines a specific trait e.g: your eye colour, height, hair colour etc. - **Phenotype**: The observable characteristics or traits of an organism, such as height or eye colour. - **Genotype**: The genetic makeup of an organism, represented by the combination of alleles.\ **Examples of Genotypes** **For Eye Colour**: - **BB**: Both alleles for brown eyes (dominant trait). - **Bb**: One allele for brown eyes and one for blue eyes (heterozygous, dominant brown shows). - **bb**: Both alleles for blue eyes (recessive trait). **For Hair Texture**: - **HH**: Both alleles for curly hair (dominant trait). - **Hh**: One allele for curly hair and one for straight hair (heterozygous, curly shows). - **hh**: Both alleles for straight hair (recessive trait). **For Flower Colour in Plants**: - **RR**: Both alleles for red flowers (dominant trait). - **Rr**: One allele for red and one for white flowers (heterozygous, red shows). - **rr**: Both alleles for white flowers (recessive trait). **For Pea Plant Height (Mendelian Genetics)**: - **TT**: Tall plant (dominant trait). - **Tt**: Tall plant (heterozygous). - **tt**: Short plant (recessive trait). - **Homozygous**: Having two identical alleles for a trait (e.g., BB or bb). 1. Sexual reproduction requires two parents and results in genetic diversity. 2. Asexual reproduction involves only one parent and produces identical offspring. 3. Meiosis creates gametes with half the original chromosome number. 4. Stem cells are undifferentiated cells that can develop into various specialized cells. 5. Heredity explains how traits are passed from parents to offspring. 6. Dominant traits are expressed with at least one dominant allele. 7. Recessive traits are expressed only when both alleles are recessive. 8. Genes are located on chromosomes and determine traits. 9. Phenotype is the observable expression of a genotype. 10. Mendel\'s experiments laid the foundation for understanding genetics. 11. **Sexual Reproduction**: Requires two parents. 12. **Eggs and Sperm**: Needed for sexual reproduction. 13. **Meiosis**: A type of cell division for reproduction. 14. **Asexual Reproduction**: Involves one parent. 15. **Fission**: Splitting of one organism into two. 16. **Budding**: New organism grows from the parent. 17. **Mendel**: Scientist who studied heredity. 18. **Heredity**: Passing of traits from parents to offspring. 19. **Dominant Trait**: Expressed with one allele. 20. **Gene**: Section of DNA determining a trait. 21. Sexual reproduction requires two parents. 22. Eggs and sperm are not produced by asexual reproduction. 23. Meiosis is a special type of cell division. 24. Asexual reproduction involves one parent only. 25. Mendel used pea plants to study heredity. 26. Stem cells can develop into various cell types. 1. Reproduction is always sexual. (False) 2. Eggs and sperm are haploid cells. (True) 3. Cloning involves genetic material from two parents. (False) 4. Stem cells are specialized cells. (False) 5. The phenotype is determined by both genes and the environment. (True) 6. Meiosis occurs in somatic (body) cells. (False) 7. Crossing over during meiosis increases genetic diversity. (True) 8. A dominant trait is always more common than a recessive trait. (False) 9. Mendel used pea plants to study heredity. (True) 10. Asexual reproduction results in greater genetic variation than sexual reproduction. (False) 1. **Meiosis**: - A cell division process that produces reproductive cells (gametes). - Results in four haploid cells with half the genetic material. 2. **Types of Asexual Reproduction**: - Fission: Splitting into two new organisms. - Budding: Growth of a new organism from the parent body. 3. **Heredity**: - The process of passing traits from parents to offspring. 4. **Genotype vs. Phenotype**: - **Genotype**: The genetic makeup of an organism. - **Phenotype**: Observable traits or physical appearance. - **Cytokinesis**: Division of cytoplasm during cell division. - **Recessive Trait**: Expressed only when two copies of the allele are present. - **Dominant Trait**: Expressed even with one allele. - **Phenotype**: Observable traits of an organism. - **Genotype**: Genetic makeup of an organism. - **Heredity**: Passing of traits from parents to offspring.